Thin Film Transistor Selective Doping Spacer Contact Resistance
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Solution Overview
Problem
Thin-film transistors (TFTs) face high contact resistance due to un-doped sections underneath spacers, which degrades their performance.
Innovation Solution
Selectively doping sections of the channel underneath spacers and source/drain contacts with Arsenic, Phosphorus, and Antimony to reduce contact resistance and improve TFT performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the channel is left un-doped underneath spacers, then the fabrication process is simpler, but the contact resistance increases
Solution Approach 1:
The patent applies selective doping to specific regions of the channel underneath the spacers and source/drain contacts, creating local variations in dopant concentration. This allows the channel to have different electrical properties in different regions: doped regions near contacts for low resistance and undoped or lightly-doped regions in the channel for proper transistor operation, thus resolving the contradiction between fabrication simplicity and contact resistance
2Reliability
If dopant concentration is increased to reduce contact resistance, then contact resistance decreases, but the threshold voltage control deteriorates
Solution Approach 1:
The patent implements spatially selective doping where high dopant concentrations are applied only in specific regions (underneath spacers and source/drain contacts) while other regions maintain lower or zero doping. This local quality approach allows high contact resistance reduction without compromising overall threshold voltage control, as the doped regions are confined to contact areas rather than the entire channel
Solution Approach 2:
The channel is segmented into different doping zones: heavily doped regions near source/drain contacts for low contact resistance, and lightly doped or undoped regions in the channel for proper threshold voltage control. This segmentation allows independent optimization of contact resistance and threshold voltage characteristics
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The selective doping of TFT channels and contacts significantly reduces contact resistance, enhancing the overall performance and efficiency of the TFTs.
Implementation Method 1
selectively doping sections of the channel underneath spacers and source/drain contacts
Data Source
AI summary
A thin film transistor (TFT) device is provided, where the TFT may include a source and a drain, a gate stack, and a semiconductor body. The gate stack may include a gate dielectric structure and a gate electrode, and the gate stack may be between the source and the drain. A first section of the semiconductor body may be adjacent to at least a section of the gate stack. A spacer may be between the gate stack and the source, where the spacer may be on the semiconductor body, and where a second section of the semiconductor body underneath the spacer may comprise dopants.